Standard shotgun shells for the 12 Gauge Shotgun vary in length from 2.5 inches to 3.00 inches, which can generally be fired from a standard semi-automatic pump or automatic shotgun.
3.25 to 3.75 inch magnum shells are also available for special guns designed to handle such size shells.
A limitation of standard shotguns relates to the amount of shells the magazine can hold, with the ordinary pump holding 4-5 shells maximum, as the magazine tube where the shells are stored is only typically about 14-16 inches long. There are magazine extenders available, but these only allow for an additional two or so shells, awkward to use because of the increased length of the magazine, can extend beyond the barrel, and can make the firearm unreliable.
The original length of the 12 gauge shell was believed to have been developed over 100 years ago, and was necessary because of the amount of powder required for the load. However, advances in black powder has resulted in substantially more power utilizing less powder. Consequently, as shown in FIG. 1, todays typical shell has a wad having a substantial cushion (8) which acts as a spacer between the lesser amount of powder (4) and the shot (2).
Because of advances in propellants including “smokeless powder” and the like, it is now possible to provide a “mini” shotgun shell (FIG. 2) having a length of, for example, 1.75 inches. Such a shell is already sold by the Aquila company of Mexico.
A problem with these “short” shells is that they cannot be used with a conventional automatic or pump action shotgun, because of their length. While they can be loaded into the magazine, allowing perhaps as much as twice the capacity of shells when compared to the longer shells, when the shells are moved one at a time by the firearm from the magazine to the firing chamber, the shorter shells jam because they tend to roll in the “litter” that is, the loading area between the magazine and the firing chamber.
One solution would be to design a firearm which would shoot these types of shells. However, a better solution would be to design a shell which stores like a “short” shell in the magazine, but loads like a conventional shell when moved from the magazine to the firing chamber, which shell could be used in conventional, off the shelf automatic and pump shotguns.
U.S. Pat. No. 5,171,934 issued 1992 teaches a “shortened shot shell having a reduced length that allows one or more extra rounds to be carried in the magazine of the standard shotgun” and teaches a longer wadding “that avoids tilting or tumbling of the wadding” in the barrel after firing, but does not teach the extension end of the present invention.
U.S. Pat. No. 6,427,600 teaches a “blank cartridge for self loading guns” wherein there is provided a “bullet-like projection being retractable. When the cartridge is fired” to facilitate recycling of the firearm. This is relevant in that the structure of the cartridge anticipates a telescoping front end, albeit for a different purpose than that taught in the present, searched for invention. PCT/B94/01779 is the PCT case on the above '600 patent.
U.S. Pat. No. 5,341,744 is referenced as it contemplates a plastic foam extension (26) emanating from the front end of the cartridge. See also U.S. Pat. No. 3,865,038.
U.S. Pat. No. 5,677,505 teaches a “reduced energy cartridge” having a recoiling inner piston, although for a different purpose than that contemplated in the present invention.
German patent 96460 teaches some interesting structure of a shot shell cartridge, but have had difficulty in translating.
U.S. Pat. No. 6,250,228 teaches a “compression shotgun cartridge” having a “compressible compression cup”, but does not appear to teach the concept of the present invention.